Genetic Properties Of Different Ganoderma Cultivars And Optimization Of Polysaccharide High-yield Producing Ganoderma Strain By Response Surface Method

Sixteen main culture Ganoderma lucidum cultivars were used as material, the genetic relationship among these16ganoderma strains was done by RAPD and ITS sequencing. Taking extrapolysaccharide and the mycelial dry weight as indexes, this experiment intended to study the ability on producting polysaccharideof16ganoderma and to screen a strain that has the high ability of producting sugar, and to optimize carbon and nitrogen source for the strains which were screened, and to optimize culture conditions by using the response surface method for the high efficiency strain.The main research results are as follows:(1) From twenty random primers, we screened four optimal primers which can amplify clear bands and have good repeatability. A total of283fagments patterns of the16strains were amplified by the four primers, and there were253polymorphic bands, accounts for89.4%of the total fingerprints. RAPD dendrogarm was established, the results showed16strains were collected at0.51level of the similarity coefficient and divided into6groups at the level of0.76similarity coefficient. The ITS fragments of16strains were amplified and sequenced, and the phylogenetic tree was construnted by MEGA5.0. The result showed that16strains were divided into2phylogenic branches. Group one contained15strains which were divided into7subgroups furtherly. Similarity coefficient between Rongbao lingzhi No.1and Ganoderma lingzhi Li245was100%, which demonstrated, from the taxonomic point, Rongbao lingzhi No.1belonged to Ganoderma lingzhi. Another brand consisted of Ganoderma atrum and Ganoderma sinense which were differert from other strains on system development. Above all, the vast majority of ganoderma lucidum are ganoderma species.(2) All the16Ganoderma lucidum strains were fermented in a basic liquid medium to produce exopolysaccharide, the results showed that the exopolysaccharides produced by Rongbao lingzhi No.1was0.5320g/L, and the biomass was2.9743g/L, so it was selected as high exopolysaccharide producing strain. Taking biomass and exopolysaccharide as the target, single factor experiments were done with4kinds of carbon source and4kinds of nitrogen source respectively. The results showed that corn starch and soybean starch are the best carbon and nitrogen source respectively.(3) After screening out appropriate carbon and nitrogen source, other factors of liquid fermentation which affect Ganoderma polysaccharide production were optimized by response surface optimization method.Firstly, taking intracellular polysaccharides and exopolysaccharide as response values separately, three main factors which seriously affect two response values were selected in nine factors by Plackett-Burman experiments. The three factors affecting intracellular polysaccharide production were corn flour, culture time and liquid medium volume; The three main factors affecting extracellular polysaccharide production were magnesium sulfate, culture time and liquid medium volume. Then three factors were approximated maximum corresponding area by the steepest grade experiment. The mathematical model was established by Box-Behnken experiment, and the results showed that when the corn flour was13.57g, culture time was9d, fluid medium volume was98ml, the yield of intracellular polysaccharide reached a maximum value139.63mg/g and when fluid medium volume was102ml, culture time was9d, the amount of magnesium sulfate is1.58g/L, exopolysaccharide production reached the maximum yield4.105g/L.